1. Field of the Invention 
The present invention relates to footwear. The invention concerns, more particularly, an article of athletic footwear having a sole structure that includes an energy absorbing split plate. 
2. Description of Background Art 
The long jump competition, a track and field sporting event, involves three distinct phases: sprinting, launching, and soaring. Initially, an athlete sprints toward a foul line that is positioned before a landing pit. Before the competitor's feet cross the foul line, the competitor launches or jumps upward, thereby becoming airborne. Finally, the competitor soars through the air and over the landing pit in an attempt to have the greatest soaring distance, which is measured from the foul line to the competitor's first point of contact with the landing pit. 
In comparison with other track and field sporting events, the long jump competition induces the greatest forces in the foot, particularly during the launch phase. As the athlete sprints toward the foul line, forces experienced by the foot are substantially similar to forces experienced during other track and field events that involve sprinting. Immediately before the foul line, and while sprinting, the athlete places one of the feet upon the ground and presses upward with the leg to provide a forceful launch. During the launch, therefore, the foot not only experiences sprinting forces, but also experiences forces associated with the upward press. The combination of these forces has the potential to be greater than the forces experienced by the foot during any other track and field sporting event.  
Conventional articles of footwear intended to be utilized during the long jump competition include an upper that receives the foot and a sole structure that is attached to the upper. The sole structure typically includes a midsole, an outsole, and a traction plate. The midsole is positioned adjacent to the foot and may be manufactured from polyurethane or ethylvinylacetate foam. The outsole is attached to the lower surface of the midsole and may be formed from a durable, wear-resistant material, such as rubber. The traction plate, a semi-rigid element attached to the outsole in the forefoot region of the footwear, includes both texturing and removable metal spikes to enhance traction. 
The primary purpose of the midsole is to attenuate shock and absorb energy associated with both the sprinting and launching phases of the long jump competition. That is, the compressive properties of the midsole act to dissipate forces experienced by the foot during the long jump competition. In designing footwear midsoles, a balance is achieved between reducing forces and stability. In general, an increase in midsole thickness imparts both an increase in force reduction and a decrease in stability. A relatively thick midsole, therefore, has greater force reduction properties and lesser stability than a relatively thin midsole. 
In comparison with midsole structures of other articles of footwear, particularly footwear designed for long distance running, the midsole of an article of long jump footwear is relatively thin. Although the forces experienced by the foot during the long jump competition, particularly during the launch phase, are significantly greater than the forces experienced during long distance running, the midsole has reduced thickness to retain stability and decrease weight. Long jump footwear, therefore, does not provide an optimal degree of shock attenuation and energy absorption, and a significant portion of the forces associated with sprinting and launch are dissipated internally by the bone of the foot. The internal dissipation of forces not only results in  excess stress upon the foot, but may also be detrimental to performance. Conventional midsole designs for long jump footwear do, however, provide stability, thereby imparting a significant degree of control during the sprinting and launching phases of the long jump competition. Accordingly, the art requires an improved article of long jump footwear that retains a high level of stability and dissipates a greater portion of the forces associated with the sprinting and launch phases of the long jump competition, thereby decreasing the overall stress in the foot and increasing the athlete's level of performance. 